PSEUDOMASS DUE TO ATELECTASIS IN PATIENTS WITH SEVERE BULLOUS EMPHYSEMA

OBJECTIVE. This study describes the atypical presentation of atelectas is as a pseudomass in patients with severe bullous emphysema. MATERIAL S AND METHODS. The radiologic studies and clinical records of 11 patie nts with severe bullous emphysema and masslike opacities representing atelectatic lung were reviewed. The diagnosis was proven by surgery in nine patients and by follow-up imaging in two patients. RESULTS. Pseu domasses were found primarily in the upper lobes and the right middle lobe (n = 10). Common features included an oblong, lenticular, or tria ngular shape (n = 8); a sharp interface with aerated lung (n = 9); hyp erexpansion of the hemithorax containing the pseudomass (n = 8); a cen tral location abutting the mediastinum (n = 8); and adjacent emphysema (n = 11). CT revealed subsegmental atelectasis in other lobes adjacen t to the bullous lung in six patients. In three patients, the pseudoma sses were associated with persistent distention of large bullae follow ing spontaneous pneumothoraces. Reexpansion of pseudomasses occurred i n seven of the eight patients who underwent resection of bullous lung. CONCLUSION. These pseudomasses most likely result from compression of the lung by adjacent large bullae. The diagnosis should be suspected when central, sharply marginated, masslike opacities that are, oblong, lenticular, or triangular are bordered by severe bullous emphysema.